Six-component microscope objective

ABSTRACT

An infinity-corrected, semi-apochromatic microscope objective having an N.A. of 0.95 has five elements and provides a magnification of 100× when used with a telescope objective having an effective focal length (efl) of 183 mm.

BACKGROUND OF THE INVENTION

This invention relates to microscope objectives and more particularly to infinity-corrected microscope objectives having an N.A. of substantially 0.95.

It is an object of this invention to provide objectives well corrected for all aberrations except lateral chromatic aberration. The residual lateral chromatic aberration between 486.1 nm and 656.3 nm is 1% of the angular magnification at 589.3 nm across usable field.

When used with a telescope lens having an effective focal length (efl) of 183 mm, the objective provides a lateral magnification of substantially 100× at 589.3 mm.

U.S. Pat. No. 3,822,931 issued July 9, 1974 relates to a six-component microscope objective having a magnification of 100× and an N.A. of 0.9. The objective of the reference differs substantially from the present invention in that the reference provides that the second, third and fifth components are singlets while the corresponding components are doublets according to the present invention. Furthermore, the final or sixth component is a convex concavo singlet in the reference while the final component is a bi-concavo singlet in the present invention.

U.S. Pat. No. 4,261,654 issued April 14, 1981 is the closest reference to the claimed structure of the present invention. While there is substantial similarity between the first, second, third and fourth components of the reference, there is a substantial disparity between the fifth and sixth components of the reference and the fifth and sixth components of the present invention. Specifically, it is noted that the fifth component of the reference comprises a convex-concavo element cemented to a convex-concavo element to provide a convex-concavo doublet while the fifth component of the present invention is a bi-convex singlet as the first element cemented to a concavo plano second element to provide a convex plano doublet. Also, the reference provides a bi-convex doublet while the present invention requires a bi-concave singlet.

THE DRAWING

FIG. 1 is an optical diagram of the objective according to the present invention.

SUMMARY OF THE INVENTION

The first lens I is a concavo-convex singlet followed by a concavo-convex doublet II followed by a bi-convex doublet III followed by a bi-convex doublet IV, a convex plano doublet V and a bi-concave singlet VI.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With respect to lens parameters, the axial thickness of successive lens elements are designated T₁ to T₁₀ and the axial spaces from the object plane designated O are S₁ to S₆. The successive lens radii are designated R₁ -R₁₆ where a minus sign (-) applies to surfaces whose center of curvature lies on the object side of the vertices. The refractive indexes and Abbe numbers of the glass in the successive lenses are designated ND₁ to ND₁₀ and ν₁ to ν₁₀.

                  TABLE I                                                          ______________________________________                                         Lens     Radius        Thickness  Spacing                                      No.      (R)           (T)        (S)                                          ______________________________________                                         I                                 S.sub.1 = 0.28                                        R.sub.1 = -1.143                                                                             T.sub.1 = -1.73                                                  R.sub.2 = 1.517                                                       II                                S.sub.2 = 0.10                                        R.sub.3 = -32.927                                                                            T.sub.2 = 1.10                                                   R.sub.4 = 5.980                                                                              T.sub.3 = 3.60                                                   R.sub.5 = -5.506                                                      III                               S.sub.3 = 0.30                                        R.sub.6 = 22.311                                                                             T.sub.4 = 1.45                                                   R.sub.7 = 5.698                                                                              T.sub.5 = 4.70                                                   R.sub.8 = -5.812                                                      IV                                S.sub.4 = 0.50                                        R.sub.9 = 33.070                                                                             T.sub.6 = 1.30                                                   R.sub.10 = 4.764                                                                             T.sub.7 = 4.00                                                   R.sub.11 = -17.305                                                    V                                 S.sub.5 = 0.20                                        R.sub.12 = 116.294                                                                           T.sub.8 = 3.50                                                   R.sub.13 = -5.200                                                                            T.sub.9 = 11.30                                                  R.sub.14 = ∞                                                    VI                                S.sub.6 = 8.00                                        R.sub.15 = -36.446                                                                           T.sub.10 = 4.00                                                  R.sub.16 = 13.612                                                     ______________________________________                                                            Index of    Abbe                                                         Lens  Refraction  No.                                                          No.   (ND)        (ν)                                          ______________________________________                                                      I     ND.sub.1 = 1.772                                                                           ν.sub.1 = 49.6                                            II    ND.sub.2 = 1.717                                                                           ν.sub.2 = 29.5                                                  ND.sub.3 = 1.697                                                                           ν.sub.3 = 56.4                                            III   ND.sub.4 = 1.788                                                                           ν.sub.4 = 47.4                                                  ND.sub.5 = 1.434                                                                           ν.sub.5 = 95.6                                            IV    ND.sub.6 = 1.785                                                                           ν.sub.6 = 26.1                                                  ND.sub.7 = 1.434                                                                           ν.sub.7 = 95.6                                            V     ND.sub.8 = 1.717                                                                           ν.sub.8 = 29.5                                                  ND.sub.9  = 1.564                                                                          ν.sub.9 = 60.8                                            VI    ND.sub.10 = 1.609                                                                          ν.sub.10 = 46.4                              ______________________________________                                     

I claim:
 1. An apochromatic microscope objective having an N.A. of substantially 0.95 which comprises a concavo-convex singlet I, a concavo-convex doublet II, a concavo-convex doublet III, a concavo-convex doublet IV, a convex plano doublet V and a bi-convex singlet VI aligned sequentially on an optical axis and having the following parameters:

    ______________________________________                                         Lens     Radius        Thickness  Spacing                                      No.      (R)           (T)        (S)                                          ______________________________________                                         I                                 S.sub.1 = 0.28                                        R.sub.1 = -1.143                                                                             T.sub.1 = 1.73                                                   R.sub.2 = -1.517                                                      II                     S.sub.2 = 0.10                                                   R.sub.3 = -32.927                                                                            T.sub.2 = 1.10                                                   R.sub.4 = 5.980                                                                              T.sub.3 = 3.60                                                   R.sub.5 = -5.506                                                      III                               S.sub.3 = 0.30                                        R.sub.6 = 22.311                                                                             T.sub.4 = 1.45                                                   R.sub.7 = 5.698                                                                              T.sub.5 = 4.70                                                   R.sub.8 = -5.812                                                      IV                                S.sub.4 = 0.50                                        R.sub.9 = 33.070                                                                             T.sub.6 = 1.30                                                   R.sub.10 = 4.764                                                                             T.sub.7 = 4.00                                                   R.sub.11 = -17.305                                                    V                                 S.sub.5 = 0.20                                        R.sub.12 = 116.294                                                                           T.sub.8 = 3.50                                                   R.sub.13 = -5.200                                                                            T.sub.9 = 11.30                                                  R.sub.14 = ∞                                                    VI                                S.sub.6 = 8.00                                        R.sub.15 = -36.446                                                                           T.sub.10 = 4.00                                                  R.sub.16 = 13.612                                                     ______________________________________                                                            Index of    Abbe                                            Lens               Refraction  No.                                             No.                (ND)        (ν)                                          ______________________________________                                         I                  ND.sub.1 = 1.772                                                                           ν.sub.1 = 49.6                               II                 ND.sub.2 = 1.717                                                                           ν.sub.2 = 29.5                                                  ND.sub.3 = 1.697                                                                           ν.sub.3 = 56.4                               III                ND.sub.4 = 1.788                                                                           ν.sub.4 = 47.4                                                  ND.sub.5 = 1.434                                                                           ν.sub.5 = 95.6                               IV                 ND.sub.6 = 1.785                                                                           ν.sub.6 = 26.1                                                  ND.sub.7 = 1.434                                                                           ν.sub.7 = 95.6                               V                  ND.sub.8 = 1.717                                                                           ν.sub.8 = 29.5                                                  ND.sub.9 = 1.564                                                                           ν.sub.9 = 60.8                               VI                 ND.sub.10 = 1.609                                                                          ν.sub.10 = 46.4                              ______________________________________                                     